BREWER BLACKBIRD. Euphagus cyanocephalus (Wagler)

Field characters.—Slightly smaller than Robin. Female about one-fourth smaller than male. Male entirely black, the plumage with a distinct sheen; iris white. Female dull brownish black; iris dark brown. No contrasted color marks in either sex. Voice: 'Song' of male a wheezy tseur or tshee; both sexes utter a harsh tchick.

Occurrence.—Common resident of the lowlands and foothills (Lower and Upper Sonoran zones, sparingly Transition) on the west slope and in the vicinity of Mono Lake (Transition) east of the mountains. Nests from Snelling up at least to the floor of Yosemite Valley (4000 feet altitude) and also in vicinity of Mono Lake. In summer and fall months ranges upward in mountains nearly to timber line. In winter abundant in San Joaquin Valley. Forages largely on meadows and grasslands. Nests singly or in small scattered colonies, but assembles in large flocks at other seasons of the year.

The Brewer Blackbird is the most widely ranging species of blackbird found in the Yosemite region. Although it remains at the lower levels for nesting, after the young are reared it ranges widely and is then apt to be found almost anywhere from the plains of the San Joaquin Valley and flats near Mono Lake up to the highest of the mountain meadows. The alert and active demeanor of the bird, its generally fearless nature, and its marked preference for foraging on open grasslands in plain view, all serve to bring it to notice wherever it may happen to be present.

The male Brewer Blackbird is without any of the color adornments which are borne by his red-winged and yellow-headed relatives. His one distinctive mark is the yellowish white iris which makes him a "white-eyed blackbird." The female is much duller colored than her mate and lacks the white of the iris, her eye being dark brown. The young birds in juvenal dress closely resemble the female parent. At no stage in their existence do the birds of this species possess any streaks or contrasted markings of any sort; therefore females and young of the Brewer are easily distinguished from those of the other blackbirds.

The voice of this blackbird is very simple. The male's song is a single whistled note, tseur or tshee. Adults and young of both sexes utter a call note, tchick, analogous to the check of the Red-wing. This note is given when the birds are in flight, as well as when they are walking about on the ground or perched on logs or fences.

Nesting activities are instituted by the Brewer Blackbird in April or early May, and in the latter month the young begin to appear abroad. Near Lagrange, in 1919, broods of young were seen out of the nest and foraging with their parents on May 8, and in Yosemite Valley a nest with six small young was found on May 22 of the same year. In 1915 the season seemed to be slightly later. Our earliest record of young out of the nest in that year was for May 26, when a fully fledged young bird was observed at Mount Bullion. On May 24 at Pleasant Valley and on May 26 at Snelling adult birds were still concerned with young in the nest. Young birds were seen on Sentinel Meadows in Yosemite Valley on May 31. A set of 4 eggs was still being incubated in a nest on the floor of the Valley on July 10. In 1916 at Mono Lake a nest with fresh eggs was found on May 18. The majority of the broods are probably brought off in the earlier part of the period here outlined.

Brewer Blackbirds show great diversity in the location of their nests. At Snelling the birds were using planted hedges of the osage orange as well as the native oak trees, and near Pleasant Valley nests were placed in clumps of mistletoe in blue oaks. In Yosemite Valley nests were seen in small yellow pines and in tangles of the cultivated blackberry. In a meadow near Mono Lake a nest was found at the base of a willow clump and only 4 inches above some standing water. Elsewhere in its range this blackbird often nests at much greater heights above the ground, even as much as 40 feet; but we found none in the Yosemite region more than about 15 feet above the ground. The species never nests in large colonies as do other blackbirds. Occasionally a few pairs have their nests in rather close proximity, but quite as often the structures are placed singly.

In Yosemite Valley, on June 18, 1915, a nest of this species was discovered in a blackberry bush near the Valley schoolhouse. It was situated in a tangle of blossoming branches and well concealed among the leaves. Dried blackberry and weed stems comprised the outer portion of the structure, while the interior was lined with both black and white horse-hairs. The nest measured 7 inches vertically, from base to rim, and the inside diameter and depth were each 3-1/2 inches. The base was 28 inches above the ground. Four eggs comprised the set; and 4 to 6 eggs or young were found in the other nests examined by us.

The Brewer Blackbird is an ardent defender of its home during nesting time, and the members of a pair, often assisted by neighboring pairs, will protest vigorously whenever an animal or person, either intentionally or innocently, approaches a nest containing eggs or young. This was well illustrated by an incident which came to our attention in Yosemite Valley. In a meadow near the Valley schoolhouse, where blackbirds of this species had been found more or less regularly, an unusual commotion was noticed at noon of June 18, 1915. Following up the disturbance it was found that four Brewer Blackbirds were pursuing a California Gray Squirrel. The birds were hovering over the animal, snapping their bills a few inches above its head, and scolding in an angry tone. The squirrel when first seen had been near a clump of blackberry bushes. From there it went dodging about in the grass of the open meadow and soon gained the top of a fence post where it perched with its tail up over its back. The long side hairs on the tail moved back and forth, either as blown by the wind or moved intentionally by the animal, and seemingly formed a shield protecting the owner from the irate birds who were continuing their demonstration. While perched on the fence the squirrel was seen to be nibbling at some small object, the nature of which could not be determined by the observer. Soon the animal leaped down, jumped across a ditch, and scrambled up a tall tree. It is entirely possible that the squirrel had not molested the blackbirds in any way but was merely eating some bit of vegetable material picked up on the ground near the nest. But the gray squirrel has been known to raid birds' nests at other times and so the concern exhibited by the adult birds may not have been entirely unwarranted. The day previous a gray squirrel had been seen pursuing a young blackbird in the same vicinity. The fledgling had escaped its pursuer only by fluttering across a pond of water and hiding in some bushes on the opposite side of the pool.

It is a well-known trait of the Brewer Blackbird to badger large birds such as hawks and crows. At Pleasant Valley, on May 24, 1915, a Cooper Hawk flying overhead was mobbed by some of these blackbirds, assisted by several Western Kingbirds. The attack was similar to that upon the Gray Squirrel as described above.

The male Brewer Blackbird during the nesting season seems to be as industrious as his mate, at least as regards attending the young, and in this he differs strikingly from the male Red-wing. As soon as the young are hatched the two parents share alike in the work of gathering food for their offspring. It is a common thing to see the members of a pair walking abreast, with the characteristic swinging gait, through the grass of a meadow, intently searching for insects or larvae. And they are remarkably keen in these searches, for rarely does one of them go far before putting its bill down and pulling something from the grass. As soon as one bird gains a mouth-load of food material it makes off to the nest site, to be followed by the mate when it too has gathered a quota. The birds usually go directly to their nests and thereby readily reveal the location of the latter.

As soon as the young are fully fledged, which in a majority of broods means about the first of July, many of the old and young begin to move up the mountains. The first Brewer Blackbird seen at Tuolumne Meadows in 1915 was observed on July 10. Four were seen in Lyell Cañon on July 14, and thereafter they were observed at many places at high altitudes; for example, in Tioga Pass (9800 feet), September 28, 1915. Their occupancy of the higher level continues until fall, as on October 9 (1915) several were seen at Ten Lakes. In 1920 the species remained in Yosemite Valley at least until October 9 (C. W. Michael, MS). Meanwhile those of the species which have remained at the lower levels gradually assemble in flocks. The approach of winter drives down those individuals which have invaded the mountains and they join the bands in the lower valleys. By December or January the flocks often number hundreds and not infrequently thousands of individuals. At Snelling about one thousand of these birds were seen on the afternoon of January 2, 1915. They were perching on the telephone wires and in the cottonwoods near, the river. On January 7, 1915, 1200 were recorded in a three and a half hour census. "Great clouds" were the words used to describe their numbers and the notebook entry states that in addition small flocks were continually passing overhead. Below Lagrange a flock of fully 500 was seen on December 22, 1915.

East of the Sierras gatherings of the same sort are to be seen, although they do not involve such large numbers. On September 13, 1915, fully 200 birds were seen in the vicinity of Silver Lake and in the adjacent sagebrush. At nightfall the birds flew in and roosted in the trees near the lake, and in the morning, between 6 and 7 o'clock, they left in small bands, flying down the cañon of Rush Creek to start anew the daily hunt for food.

During the summer months insects form the principal item of food for the Brewer Blackbird. The young birds seem to be fed largely if not exclusively on this sort of diet. The up-mountain movement of the birds in summer is probably induced by the abundance of insect food then to be obtained in the alpine meadows. At Silver Lake many of the blackbirds were catching grasshoppers among the sagebushes. At Mono Lake, on June 30, 1916, about 50 Brewer Blackbirds were seen feeding on the "Mono Lake fly," myriads of which were hatching out on that date. The birds seemed to be seeking certain individual adult insects, or perhaps the larvae, among the great mass of debris, chiefly pupa cases, which lay along the lake shore. Below Lagrange on December 22, 1915, a large flock of these birds was seen following a gang plow and feeding on worms and insects turned up from beneath the surface of the ground.